Persistent pain is a significant problem for many osteoarthritis patients. The proposed study represents the second phase in our research on a newly developed cognitive - behavioral therapy (CBT) intervention that systematically involves spouses in training in pain coping skills (CBT- spouse training). Our initial study of CBT-spouse training suggests that this intervention appears to be more effective in reducing psychological disability and pain than CBT without spouse involvement or an arthritis education involving the spouse. However, patients receiving the CBT-spouse training intervention failed to show improvements in physical disability. The proposed study continues our research on CBT and is designed to test the hypothesis that an aerobic exercise intervention will increase the efficacy of CBT-spouse training in reducing physical disability. In this study, 160 osteoarthritic knee pain patients will be randomly assigned to four conditions: a) CBT-spouse training alone, b) CBT-spouse training plus aerobic exercise, c) aerobic exercise alone, and d) standard care control. The study: l) will evaluate whether the CBT-spouse training plus aerobic exercise intervention is more effective in reducing physical disability than CBT-spouse training or aerobic exercise alone, 2) will determine how changes in aerobic fitness, self-efficacy, and spousal responses to pain behaviors relate to long-term (6 months) improvements in pain and disability, and 3) will use newly developed daily study methods to analyze the long-term effects of CBT-spouse training and aerobic exercise on daily pain coping. If we find that CBT and aerobic exercise have synergistic effects in -osteoarthritis patients, future studies could evaluate this treatment combination with other rheumatic disease populations such as rheumatoid arthritis, lupus, or fibromyalgia. Future studies could also test the efficacy of home based CBT/spouse training-aerobic exercise programs. With training centered in the home, the intervention could be streamlined and made more readily available to the large population of patients having osteoarthritis. Finally, future studies could test whether early intervention with a combined CBT-spouse training and aerobic exercise intervention may be effective in preventing pain and disability in osteoarthritis patients. The findings of this study could lead to improved treatments that not only decrease pain, but also improve function. These results could have direct implications for clinical management of patients having osteoarthritis pain, and they could enlarge our repertoire of methods for treating pain and disability in general.